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Combined with ultrasonic pulse-echo technique, reflection spectrum analysis was introduced to evaluate TiAl and 40Cr diffusion bonding quality. Frequency dependence of reflection coefficient was used to distinguish perfect bonding from imperfect bonding. It is found that the reflection coefficient from perfect bonding interface does not vary with frequency. When the size of imperfections is much smaller than the wavelength of ultrasound, the reflection coeffwient depends on frequency. When the size of imperfections is the same order of or even larger than the wavelength of ultrasound, the reflection coeffwient does not exhibit frequency dependence. However the amplitude of imperfect interface is higher than the amplitude of perfect bonding interface. A combination of reflection spectrum analysis and ultrasonic pulse-echo technique provides more accurate information about the bonding quality of dissimilar materials. 相似文献
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为了解决界面回波幅度均值无法评价异种材料扩散焊接头强度的问题,文中提出一种接头强度评价与预测方法.该方法基于二叉树支持向量机构建界面缺陷的识别模型,根据识别结果计算界面的焊合率,建立焊合率与抗剪强度的关系.采用线性拟合的方法获得抗剪强度的经验公式,用于预测接头强度.结果表明,构建的缺陷识别模型可以有效地识别出扩散焊界面未焊合、弱接合和微孔缺陷,焊合率与接头抗剪强度具有相关性,抗剪强度随着焊合率的增加而增加.实现了接头强度的预测,预测强度与实测值吻合较好. 相似文献
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Combined with ultrasonic pulse-echo technique, reflection spectrum analysis was introduced to evaluate TiAl and 40Cr diffusion bonding quality. Frequency dependence of reflection coefficient was used to distinguish perfect bonding from imperfect bonding. It is found that the reflection coefficient from perfect bonding interface does not vary with frequency. When the size of imperfections is much smaller than the wavelength of ultrasound, the reflection coefficient depends on frequency. When the size of imperfections is the same order of or even larger than the wavelength of ultrasound, the reflection coefficient does not exhibit frequency dependence. However the amplitude of imperfect interface is higher than the amplitude of perfect bonding interface. A combination of reflection spectrum analysis and ultrasonic pulse-echo technique provides more accurate information about the bonding quality of dissimilar materials. 相似文献
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为了解决异种材料扩散焊质量超声波检测时,从回波幅度无法判断界面是否存在微小缺陷的问题,采用支持向量机技术构建了扩散焊界面缺陷识别模型.以TiAl和40Cr扩散焊接头为研究对象,采用超声波水浸聚焦法采集扩散焊界面信号,从信号中提取4个特征值,优化样本数量和核参数后,训练扩散焊界面缺陷识别模型.扩散焊试样界面信号经模型识别后,根据C扫描图像的位置重构识别图像.结果表明,该模型有效地识别出未焊合、弱接合和微孔缺陷,3种缺陷的正确识别率分别为93%、90.5%和91.5%,识别图像直观地显示了界面的缺陷.TiAl/40Cr扩散焊界面缺陷识别模型实现了扩散焊试样界面缺陷的智能识别. 相似文献
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